The present invention relates to sample entry devices and, more particularly, to a sample entry device with a single plug-in site for the automated input of medical samples, typically samples of body fluids, or quality control media from diverse sample vessels.
Sample entry devices are known from medical laboratories, for example, where they may be used with blood analyzers for the analysis of whole blood, serum, plasma, or for other measurements of body fluids, such as liquor, pleura fluid, urine, etc. Some of these analyzers are designed for only one kind of sample vessel; they may for instance only permit sample input by means of a syringe.
For this reason the wish has often been expressed that sample entry devices be developed which should be suitable for sample input from diverse sample vessels, without requiring time-consuming adaptations.
In EP 0 297 082 an analyzer for samples of body fluids is disclosed, which has a rotatable docking disk, which in diverse rotational positions can be connected with a fitting of the sample feed line of the analyzer. Via this docking disk the sample can be entered, i.e., it is either aspirated by means of a peristaltic pump or injected into the sample input. The disadvantage of a sample entry device of this kind is that closed sample vessels such as so-called Vacutainers® or Monovettes® cannot be used, and that cleaning the sample input opening in order to avoid cross-contamination by sample residues is relatively difficult and costly.
A sample entry device similar to that of EP 0 297 082 is described in DE 38 90 175 C1. In that device a distributor disk is provided, which rotates about an axle and has a plurality of input elements positioned at equal distances relative to the axle, which elements may be connected to the media to be entered by means of suitable connectors. The distributor disk is held in the housing of the analyzer by means of a carrier shaft, the analyzer further being provided with a control unit for rotational and lifting motion of the distributor disk. In one rotational position the distributor disk has a slot, such that the sample input opening for introducing, the sample by means of a pipette or ac syringe is uncovered. The sample input device described in DE 38 90 175 C1 may thus be used to aspirate the sample from a capillary or to inject it by means of a syringe, with a conical opening being provided to receive and seal the capillary or the syringe, which opening is connected directly to the measuring cells of the analyzer via a rigid, gas-tight line. This entry device is not suited for another type of input preferred in laboratories, however. i.e., sample input from closed sample vessels, for instance Vacutainers® or Monovettes®.
In an entry device known from EP 0 564 439 A2 a flap swiveling around a fixed axle is provided for entering washing and reference media, which are fed to an elastic input element of the analyzer when the flap is closed. When the flap is open the input element can be freely accessed for aspiration from capillaries or injection by means of a syringe. The disadvantages mentioned above for EP 0 297 082 remain the same.
There are also known sample entry devices which permit aspiration of the sample from a syringe. There is a great variety of entry devices in which a swivelled input needle is provided, such that in the diverse positions of the needle sample fluid tray be aspirated into the analyzer from diverse sample vessels. In this context U.S. Pat. No. 4,499,053 A should be mentioned, which describes a relatively complicated lifting mechanism with a guide link structure, the sample being aspirated either from a capillary or from a syringe. To this end the intake needle is provided with an intake element, which with its central orifice is axially guided on the intake needle and controlled by a link structure. By means of a handle on the link structure the intake needle may be tilted up from a rest position, in which it is connected with a fitting for a rinsing solution, to various other positions in which—guided by the link structure—the intake element assumes diverse positions along the axis of the intake needle. In one lift position the needle tip is completely exposed, such that the needle may be dipped into open sample vessels to aspirate the sample. In another lift position the needle tip is located within the central orifice of the intake element and a sample capillary may be inserted and held in the remaining open space of the central orifice. The sample may then be aspirated by the pump of the analyzer. Finally there is provided a further lift position, in which the intake needle assumes an essentially horizontal position and the intake element exposes a small piece of the needle tip. The cone of a syringe may now be slipped over the needle tip and pressed against, the outer face of the intake element, whereupon the sample may be injected into the analyzer. As a disadvantage it should be mentioned that the syringe is not supported by the entry device, and that the outer face of the intake element will provide only an insufficient seal, such that sample residues may contaminate the entry device.
A serious disadvantage of the entry device according to U.S. Pat. No. 4,499,053 A lies in the fact, however, that it is not possible to introduce samples from closed sample vessels.
In U.S. Pat. No. 5,391,499 A an entry system is described n which sample input is possible with the use of two different sample vessels, i.e., with a syringe (see FIG. 1) or with a sample capillary (see FIG. 2). By means of a rotatable element in the area of sample entry it can be ascertained automatically from the diameter of the sample vessel whether a syringe or a sample capillary has been inserted into the input orifice, and a different input program can be initiated for each type of input. The intake needle is either moved forward in longitudinal direction by means of a drive unit to penetrate into the syringe, or is retracted to make room for a capillary. A disadvantage of the entry system according to U.S. Pat. No. 5,391,499 A, which has to be rinsed with a washing solution before each new measurement, lies in the fact that it will not permit sample input from a Vacutainer®, for example.
It is further known in the art to use different adaptors for different sample vessels, which must be attached to the intake element of the analyzer or must be inserted into it. This will however call for increased manipulation efforts and will increase the risk of operator errors.
In the context of automated sample withdrawal from closed test tubes it is also known to puncture the stopper of the test tube by means of a robot mechanism at whose end a sharpened hollow needle is provided, and to withdraw the sample. In EP 0 452 892 B1, for instance, a device is described for sample withdrawal from open or closed vessels, whose needle can penetrate the sealing cap of a Vacutainers® but is apparently not made for insertion into the small-diameter opening of a syringe. As a further disadvantage this known sample entry device requires a special washing station for the needle.
Finally, from EP 1 347 282 A2 there is known a sample entry device with a stationary intake needle located on the sample entry side of the analyzer. The intake needle is provided with an elastic intake element which slides axially on the needle and has a conical input opening. Furthermore a holding element is provided, which is moveable relative to the intake element and can be shifted axially parallel to the needle, and which in a first position permits free access to the intake element and in a second position pieces a conical orifice for receiving a syringe above the intake element. In the first position of the holding element, in which the conical input opening of the elastic intake element is exposed, the sample may advantageously be aspirated from a capillary or injected by means of a syringe. In the second position, which is reached by a translational or rotational shift of the holding element starting from the first position, the holding element receives the syringe, which is placed above the intake needle and slipped over the intake needle, by a subsequent lifting motion of the holding element. Following this the sample may be aspirated from the interior of the syringe. Direct input of samples from closed sample vessels, such as Vacutainers® or Monovettes®, is not possible, however. Besides, the stationary intake needle has to be cleaned prior to each sample entry action.